He killed 12 people, including a sheriff’s sergeantwho responded to the gunfire. Police later found the shooter dead inside the bar, possibly from a self-inflicted wound.

“It’s a horrific scene in there,” Dean said. “There is blood everywhere and the suspect is part of that.

“We don’t know who shot anybody at this point.”

A witness to the shootings, Taylor Von Molt, 21, who said she was a promotor at the bar, said the gunman wore a black mask with a bandana covering the bottom of his face, and a black hoodie.

The dead officer was identified as Sergeant Ron Helus, a 29-year veteran of the department, Dean told reporters. Helus and a California Highway Patrol officer were the first to arrive at the bar and went inside just before 11:30 p.m.

The rampage took place at the Borderline Bar & Grill in Thousand Oaks, about 40 miles northwest of Los Angeles. Authorities don’t yet have a motive for the shooting.

“I just started hearing these big pops. Pop pop pop,” he said. “There was probably three or four. I hit the ground. I look up. The security guard … was shot, he was down. The gunman was throwing smoke grenades all over the place. I saw him point to the back at the cash register and he just kept firing.”